This invention relates to coated abrasives and more particularly to coated abrasives in which the abrasive surface comprises a plurality of generally regular composite structures each of which comprises abrasive grain dispersed within a cured binder. The shape, spacing, size and composition of the composites can be manipulated to achieve a wide range of abrasive properties and for this reason the products are frequently referred to as xe2x80x9cengineered abrasivesxe2x80x9d and this convention is adopted herein.
Engineered abrasives share a drawback, or more accurately an inconvenience, with all coated abrasives. Once they have been placed in position on a backup pad in the case of an abrasive disc, or on a machine in the case of a belt, it is difficult to identify the nature or source of the product being used without taking the abrasive off the device to which it is attached.
Various options have been identified to overcome this problem. These include most notably the use of different colors to indicate different grit sizes or types of surface treatment. This technique has been used commercially with some success but the approach depends on the operator knowing the xe2x80x9ccodexe2x80x9d used by the manufacturer. With the advent of engineered abrasives a further technique becomes available for communicating information to the user in a convenient and very direct manner and this approach is at the heart of the present invention.
The present invention provides an engineered abrasive having an abrasive surface comprising a plurality of shaped abrasive structures wherein the structures are modified to create visible product indicia on the surface.
In the context of this invention the term xe2x80x9cindiciaxe2x80x9d is intended to convey any information, corporate name, trademark, or other product identifier appropriate to the coated abrasive bearing the indicia.
The modification can be for example in the form of structures of a different size, shape or spacing or a combination of these characteristics. It would also be considered a xe2x80x9cmodificationxe2x80x9d to eliminate individual structures altogether to create a pattern on the surface corresponding to the desired indicia. The most convenient modification is to change the shape of the structure. For example, if the structures on the surface are all square-based pyramids, the shapes within the space occupied by the indicia could be conical. If the surface comprises structures of identical size, (in terms of the distance of the distal end from the backing), and the indicia are not used extensively, the structures could additionally or alternatively be made uniformly smaller, (that is, with the distal ends closer to the backing), within the space occupied by the indicia. It would also be effective to connect adjacent structures by ridges so as to spell out letters or numbers. This can be particularly effective when the tool is an abrasive belt and the pattern on the surface is one of parallel ridges running across the width of the belt at an acute angle to the sides of the belt. A further variant would be to create grooves in the surface of selected structures such that the grooves spelled out the desired indicia. This technique can also be used to indicate the end of the useful life of the coated abrasive such that the product is deemed worn out when the grooves by which the indicia are created, are no longer visible
The indicia used are not restricted other than by law and good taste. It can for example be the name of the manufacturer, the trademark associated with the product and/or the grit size. If the amount of information conveyed in this way is too extensive and the extent of modifications required results in local disruption of the grinding patterns, then the overall drop in performance of the product would make the option unattractive. However if the performance effect is insignificant and the value of the information conveyed important, this technique offers a very valuable convenience to the user and an excellent means of differentiating the products of one manufacturer from those of another.